Single-color option for Tint effect
I often just want to add a simple color tint to an object (eg make something a little blue). This seems like a very basic need to me.
The 'Fill' effect is no good as you can't change the opacity.
The 'Tint' effect requires two colors, meaning you can't see a preview while you pick a color, as you need to copy and paste your color into two boxes.
Sure, there are workarounds, like using a solid. But isn't this kind of thing precisely what effects are made for? If we have an adjustment layer containing various effects, why shouldn't we be allowed to add a simple tint to it?
What I'm asking for is that the Tint effect gets an option called something like "Number of colors", allowing either 1 or 2 colors.
the dudes commented
Use CC Toner, which is a standard effect. You can set it to 2,3,5 or single color.